What is Calcium Carbide Powder and Why Do We Use Them?

Chemical compound Calcium carbide Names Preferred IUPAC name Calcium acetylide Systematic IUPAC name Calcium ethynediide Other names

• Calcium percarbide
• Calcium carbide
• Calcium dicarbide

Identifiers

• 75-20-7 Y

3D model (JSmol) ChemSpider

•  Y

ECHA InfoCard 100.000.772 EC Number

• 200-848-3

PubChem CID UNII

• 846WNV4A5F Y

CompTox Dashboard (EPA)

• InChI=1S/C2.Ca/c1-2;/q-2;+2 YKey: UIXRSLJINYRGFQ-UHFFFAOYSA-N Y
• InChI=1/C2.Ca/c1-2;/q-2;+2Key: UIXRSLJINYRGFQ-UHFFFAOYAI

• [Ca+2].[C-]#[C-]

Properties CaC2 Molar mass 64.100 g·mol−1 Appearance White powder or colorless crystals, grey/brown/black crystals if impure Density 2.22 g/cm3 Melting point 2,160 °C (3,920 °F; 2,430 K) Boiling point 2,300 °C (4,170 °F; 2,570 K) Reacts to produce Acetylene Structure[1] Tetragonal (I phase)
Monoclinic (II phase)
Monoclinic (III phase) I4/mmm (I phase)
C2/c (II phase)
C2/m (III phase) 6 Thermochemistry Std molar
entropy (S⦵298) 70 J/(mol·K) Std enthalpy of
formation (ΔfH⦵298) −63 kJ/mol Hazards Occupational safety and health (OHS/OSH): Main hazards Reacts with water to release acetylene gas[2] GHS labelling: Danger H260 NFPA 704 (fire diamond) 305 °C (581 °F; 578 K) (acetylene) Related compounds Related compounds Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y   (what is YN ?) Chemical compound

Calcium carbide, also known as calcium acetylide, is a chemical compound with the chemical formula of CaC2. Its main use industrially is in the production of acetylene and calcium cyanamide.[3]

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The pure material is colorless, while pieces of technical-grade calcium carbide are grey or brown and consist of about 80–85% of CaC2 (the rest is CaO (calcium oxide), Ca3P2 (calcium phosphide), CaS (calcium sulfide), Ca3N2 (calcium nitride), SiC (silicon carbide), C (carbon), etc.). In the presence of trace moisture, technical-grade calcium carbide emits an unpleasant odor reminiscent of garlic.[4]

Applications of calcium carbide include manufacture of acetylene gas, generation of acetylene in carbide lamps, manufacture of chemicals for fertilizer, and steelmaking.

Production

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Calcium carbide is produced industrially in an electric arc furnace from a mixture of lime and coke at approximately 2,200 °C (3,990 °F).[5] This is an endothermic reaction requiring 110 kilocalories (460 kJ) per mole[6] and high temperatures to drive off the carbon monoxide. This method has not changed since its invention in :

CaO + 3 C → CaC2 + CO

The high temperature required for this reaction is not practically achievable by traditional combustion, so the reaction is performed in an electric arc furnace with graphite electrodes. The carbide product produced generally contains around 80% calcium carbide by weight. The carbide is crushed to produce small lumps that can range from a few mm up to 50 mm. The impurities are concentrated in the finer fractions. The CaC2 content of the product is assayed by measuring the amount of acetylene produced on hydrolysis. As an example, the British and German standards for the content of the coarser fractions are 295 L/kg and 300 L/kg respectively (at 101 kPa pressure and 20 °C (68 °F) temperature). Impurities present in the carbide include calcium phosphide, which produces phosphine when hydrolysed.[7]

This reaction was an important part of the Industrial Revolution in chemistry, and was made possible in the United States as a result of massive amounts of inexpensive hydroelectric power produced at Niagara Falls before the turn of the 20th century.[8] The electric arc furnace method was discovered in by T. L. Willson, and independently in the same year by H. Moissan.[9][10][11] In Jajce, Bosnia and Herzegovina, the Austrian industrialist Josef Kranz and his "Bosnische-Elektrizitäts AG" company, whose successor later became "Elektro-Bosna", opened the largest chemical factory for the production of calcium carbide at the time in Europe in . A hydroelectric power station on the Pliva river with an installed capacity of 8 MW was constructed to supply electricity for the factory, the first power station of its kind in Southeast Europe, and became operational on 24 March .[12]

Crystal structure

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Calcium carbide is a calcium salt of acetylene, consisting of calcium cations Ca2+ and acetylide anions −C≡C−. Pure calcium carbide is a colourless solid. The common crystalline form at room temperature is a distorted rock-salt structure with the C2−2 units lying parallel.[13] There are three different polymorphs which appear at room temperature: the tetragonal structure and two different monoclinic structures.[1]

Applications

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Production of acetylene

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The reaction of calcium carbide with water, producing acetylene and calcium hydroxide,[5] was discovered by Friedrich Wöhler in .

CaC2(s) + 2 H2O(l) → C2H2(g) + Ca(OH)2(aq)

This reaction was the basis of the industrial manufacture of acetylene, and is the major industrial use of calcium carbide.

Today acetylene is mainly manufactured by the partial combustion of methane or appears as a side product in the ethylene stream from cracking of hydrocarbons. Approximately 400,000 tonnes are produced this way annually (see acetylene preparation).

In China, acetylene derived from calcium carbide remains a raw material for the chemical industry, in particular for the production of polyvinyl chloride. Locally produced acetylene is more economical than using imported oil.[14] Production of calcium carbide in China has been increasing. In output was 8.94 million tons, with the capacity to produce 17 million tons.[15]

In the United States, Europe, and Japan, consumption of calcium carbide is generally declining.[16] Production levels in the US during the s were 236,000 tons per year.[13]

Production of calcium cyanamide

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Calcium carbide reacts with nitrogen at high temperature to form calcium cyanamide:[5]

CaC2 + N2 → CaCN2 + C

Commonly known as nitrolime, calcium cyanamide is used as fertilizer. It is hydrolysed to cyanamide, H2N−C≡N.[5]

Steelmaking

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Calcium carbide is used:

• in the desulfurization of iron (pig iron, cast iron and steel)[7]
• as a fuel in steelmaking to extend the scrap ratio to liquid iron, depending on economics.
• as a powerful deoxidizer at ladle treatment facilities.

Carbide lamps

[edit] Main article: Carbide lamp

Calcium carbide is used in carbide lamps. Water dripping on carbide produces acetylene gas, which burns and produces light. While these lamps gave steadier and brighter light than candles, they were dangerous in coal mines, where flammable methane gas made them a serious hazard. The presence of flammable gases in coal mines led to miner safety lamps such as the Davy lamp, in which a wire gauze reduces the risk of methane ignition. Carbide lamps were still used extensively in slate, copper, and tin mines where methane is not a serious hazard. Most miners' lamps have now been replaced by electric lamps.

Carbide lamps are still used for mining in some less wealthy countries, for example in the silver mines near Potosí, Bolivia. Carbide lamps are also still used by some cavers exploring caves and other underground areas,[17] although they are increasingly being replaced in this use by LED lights.

Carbide lamps were also used extensively as headlamps in early automobiles, motorcycles and bicycles, but have been replaced entirely by electric lamps.[18]

Other uses

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Calcium carbide is sometimes used as source of acetylene, which like ethylene gas, is a ripening agent.[19] However, this is illegal in some countries as, in the production of acetylene from calcium carbide, contamination often leads to trace production of phosphine and arsine.[20][21] These impurities can be removed by passing the acetylene gas through acidified copper sulfate solution, but, in developing countries, this precaution is often neglected.

Calcium carbide is used in toy cannons such as the Big-Bang Cannon, as well as in bamboo cannons. In the Netherlands calcium carbide is used around new-year to shoot with milk churns.[22]

Calcium carbide, together with calcium phosphide, is used in floating, self-igniting naval signal flares, such as those produced by the Holmes' Marine Life Protection Association.

Calcium carbide is used to determine the moisture content of soil. When soil and calcium carbide are mixed in a closed pressure cylinder, the water content in soil reacts with calcium carbide to release acetylene whose pressure can be measured to determine the moisture content.[23][24]

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Calcium carbide is sold commercially as a mole repellent.[25] When it comes into contact with water, the gas produced drives moles away.[26]

References

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What is Calcium carbide?

Calcium carbide, also known as Calcium Acetylide is an Industrial Chemical, used for the production of acetylene and calcium cyanamide.

Calcium carbide

What is Calcium carbide used for?

Following are the application of Calcium carbide:

• Calcium carbide is primarily used to generate acetylene gas, a reducing agent used in carbide lamps and fruit maturation.
• It is also equally important in the manufacturing of chemical fertilizers.
• It is utilized in steelmaking to extend the scrap ratio to liquid iron.
• It is employed as a potent deoxidizer in ladle treatment facilities.
• It is equally effective in finding out the moisture content of the soil.
• It is used to remove sulfur from iron (pig iron, cast iron, and steel).
• It is effectively utilized in floating and self-igniting naval signal flares, along with calcium phosphide.
• It is also employed as a mole repellant.

What is the Chemical Formula of Calcium carbide?

Calcium carbide has the molecular formula CaC2.

Is Calcium carbide harmful to life?

Contact of skin with calcium carbide can be irritating and burning. Exposure to the eyes is even more hazardous because it can cause severe burns and perhaps permanent damage. Likewise, inhaling a tiny amount of this chemical might irritate the lungs, whereas increased exposure can result in a build-up of fluid in the lungs, causing pulmonary edema, a medical emergency. Above all, calcium carbide is carcinogenic to humans and should be avoided to the greatest extent possible.

Where is Calcium carbide found? What does Calcium carbide look like?

In industries, calcium carbide can be produced by combining lime and coke in an electric arc furnace at a high temperature of around °C. It is also a byproduct of calcium-silicon alloy smelting.

Calcium carbide has a garlic-like odor and looks like a grayish-black hard lump or crystalline powder. In its pure condition, however, it is frequently colorless.

Calcium carbide

What are the Hazardous effects of Calcium carbide?

Calcium carbide is non-combustible itself, but it poses a fire and explosion threat. When exposed to water or moisture, it forms a flammable acetylene gas along with other poisonous gases.  Even when the air is moist, a container of calcium carbide can burst in fire, emitting hazardous fumes.

What are precautionary measures necessary to be taken to handle Calcium carbide?

To avoid any undesired situation, calcium carbide should only be stored and handled by a skilled professional. Adequate industrial hygiene procedures and the use of protective equipment are essential at all times. Furthermore, personal protective equipment should be composed of materials that won’t be decayed or infiltrated by this chemical.

What will happen if Calcium carbide is heated?

The reaction of Calcium carbide is usually exothermic which causes the release of a tremendous amount of heat even when reacted with water. However, when heated at high temperatures, calcium carbide reacts with nitrogen to produce cyanamide, which is used as a fertilizer.

Is Calcium carbide soluble compound?

Calcium carbide decomposes in water to form acetylene gas and calcium hydroxide.

Where can I buy Calcium carbide?

Here at Camachem, Calcium carbide is for sale. If you need a large quantity of these chemicals, they can be shipped in iron drums of various capacities. Camachem has been directly exporting Calcium carbide to consumers all over the world.

Calcium carbide Packaging

How much does Calcium carbide cost?

The price is usually affected by the cost of raw materials, logistics, and other industrial inputs. The cost per tonne is approximately $150.00.

Calcium carbide cost

What is the PH of Calcium carbide?

Calcium carbide is extremely basic, having ph. of roughly 12.4, and is, therefore, used for acid neutralization.

Is Calcium carbide an Electrolyte compound?

Although calcium carbide is not an electrolytic compound, it is utilized as an anode in some applications.

Can Calcium carbide go down the drain?

Since it is strongly encouraged not to let calcium carbide enter the environment, it should be reused as much as possible. In the event of a spill or disposal, it should be sealed and disposed of according to federal, state, and municipal rules.

What is the difference between Calcium carbide and Calcium carbonate?

These two compounds have vastly different appearances, availability, and manufacturing processes. Calcium carbide is a dark crystal powder that reacts aggressively with water, whereas calcium carbonate is a white substance that is insoluble in water. Similarly, how these two compounds are used differ.

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